1. Field of Invention
This invention relates to seaming means, a method and apparatus for forming the seam, and more particularly to a self-locking seam which can be used to join the two ends of a piece of fabric to create an endless belt.
2. Description of the Prior Art
Endless belts made out of woven fabric materials are used in a number of fields. Their use is especially prominent in the papermaking industry where such belts are used in the forming, pressing and drying of continuous sheets of paper. In order to insure that the belts in this industry have a long useful life the seams must be strong. On the other hand, the seams cannot exhibit substantial surface variations, or they will mark the paper.
One type of seam which has proven to be fairly reliable in the paper industry is the so-called pintle seam, such as the one described in the commonly assigned U.S. Pat. No. 4,123,022. These seams comprise intermeshing juxtaposed loops formed on each end of the fabric. There are several methods which may be used to secure the loops to the belt fabric. For example, the loops may be sewn on a webbing and then the webbing may be secured to the belt fabric. Another method is to fold over the ends of the fabric and to insert a spiral coil formed of interconnected loops between the fabric threads. A third method comprises reweaving the machine direction yarns back into the fabric after they are shaped into loops. All these seam loops have a distinct disadvantage in that they are very time consuming to mesh together. For example, after the loops have been secured to the fabric ends by using one of the methods outlined above, depending on the width and fineness of the fabric, it takes between one-half and eight hours to join the ends to form the belt. Furthermore, at least two persons are needed to mesh loops and push the pin through the loops respectively, and several other persons are required to hold down the rest of the fabric. This is also compounded if the meshing location is not in a convenient place, i.e. working upside down.